3221072721 has 24 divisors (see below), whose sum is σ = 4748103360. Its totient is φ = 2103462816.

The previous prime is 3221072719. The next prime is 3221072737. The reversal of 3221072721 is 1272701223.

It is not a de Polignac number, because 3221072721 - 2¹ = 3221072719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3221072741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 309220 + ... + 319466.

It is an arithmetic number, because the mean of its divisors is an integer number (197837640).

Almost surely, 2^3221072721 is an apocalyptic number.

It is an amenable number.

3221072721 is a deficient number, since it is larger than the sum of its proper divisors (1527030639).

3221072721 is a wasteful number, since it uses less digits than its factorization.

3221072721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10965 (or 10962 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 27.

The square root of 3221072721 is about 56754.4951611764. The cubic root of 3221072721 is about 1476.8402152612.

Adding to 3221072721 its reverse (1272701223), we get a palindrome (4493773944).

The spelling of 3221072721 in words is "three billion, two hundred twenty-one million, seventy-two thousand, seven hundred twenty-one".